[PATCH v3 23/35] x86/bugs: Add attack vector controls for taa

David Kaplan
2025-01-08T20:25:52Z

Use attack vector controls to determine if taa mitigation is required.

Signed-off-by: David Kaplan <david.kaplan@amd.com>
---
arch/x86/kernel/cpu/bugs.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 298acb80d126..af5aaa0397c7 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -572,8 +572,12 @@ static void __init taa_select_mitigation(void)
return;

/* Microcode will be checked in taa_update_mitigation(). */
- if (taa_mitigation == TAA_MITIGATION_AUTO)
- taa_mitigation = TAA_MITIGATION_VERW;
+ if (taa_mitigation == TAA_MITIGATION_AUTO) {
+ if (should_mitigate_vuln(X86_BUG_TAA))
+ taa_mitigation = TAA_MITIGATION_VERW;
+ else
+ taa_mitigation = TAA_MITIGATION_OFF;
+ }

}

@@ -620,7 +624,8 @@ static void __init taa_apply_mitigation(void)
*/
setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF);

- if (taa_nosmt || cpu_mitigations_auto_nosmt())
+ if (taa_nosmt || cpu_mitigations_auto_nosmt() ||
+ cpu_mitigate_attack_vector(CPU_MITIGATE_CROSS_THREAD))
cpu_smt_disable(false);
}

--
2.34.1